Schottky barrier diode having a guard ring structure

Abstract

A Schottky barrier diode is provided which has a substrate including a first-conductivity-type low concentration layer and a first-conductivity-type high concentration layer, and a guard ring region, comprising a second-conductivity-type diffusion layer having an impurity surface concentration of not greater than 5x1017/cm3, formed in the first-conductivity-type low concentration layer. The first-conductivity-type low concentration layer has a thickness large enough to prevent a depletion layer that appears in the low concentration layer upon application of the maximum reverse voltage from reaching the first-conductivity-type high concentration layer.

What is claimed is:  
     
       1. A Schottky barrier diode comprising: 
       a substrate including a first-conductivity-type low concentration layer and a first-conductivity-type high concentration layer; and  
       a guard ring region comprising a second-conductivity-type diffusion layer having an impurity surface concentration of not greater than 5×10 17 /cm 3 , formed in said first-conductivity-type low concentration layer;  
       wherein said first-conductivity-type low concentration layer has a thickness large enough to prevent a depletion layer that appears in the low concentration layer upon application of a maximum reverse voltage from reaching said first-conductivity-type high concentration layer; and  
       wherein said thickness of said first-conductivity-type low concentration layer is controlled to be not smaller than a value represented by:  
       
         
             x +0.55·(ρ·V) ½   
         
       
       where “x” is a thickness of said diffusion layer of said guard ring region, “ρ” is a resistivity of said first-conductivity-type low concentration layer, and “V” is a maximum applied voltage. 
     
     
       2. A Schottky barrier diode as defined in claim  1 , wherein the thickness of said diffusion layer of said guard ring region is controlled to be not greater than 1.5 μm.